This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, provides funds for a geophysical site survey of the MacKay Sea Valley that is needed to evaluate the potential of this area to yield important sedimentary records of paleoenvironmental records of ice sheet fluctuations during Quaternary time (approximately the last 1.6 million years of Earth's history). Quaternary geological successions have been a recent focus for providing high-resolution records of past environmental changes on which to base future predictions, and to assist in deciphering natural variability from human-induced changes. This study is aimed at extending the data base of high-resolution marine geological records of environmental change that have been established recently in Antarctica, and to address Quaternary and perhaps older environmental changes.
The current phase of the work, to achieve the goals outlined above, is specifically aimed at collecting information in a detailed site survey to be used for precisely locating the best drill sites, and also to provide data to use in an engineering evaluation of drilling and coring systems to meet sampling requirements. The location proposed for this study is Mackay Sea Valley (MSV), which is believed to have been formed by erosion associated with early Cenozoic expansion of Mackay Glacier, a major outlet glacier of the East Antarctic Ice Sheet. MSV extends through Granite Harbor and out to the western Ross Sea. Since being eroded, the valley has experienced sediment accumulation, at least in the Quaternary and possibly through earlier times during late Cenozoic.
Coring sites in the MSV are excellent targets because: (1) their great water depth and near shore location, as well as the polar climate, appears to have led to the trough being a site of preservation for the highest resolution record of Quaternary marine environmental change known in the Ross Sea sector; (2) the sedimentation regime is one of the most intensely studied coastal settings in Antarctica; (3) there is a preliminary geophysical site survey, and (4) based on previous piston core work, the sediments appear to have the potential for good chronological control. Ultimately, the main goals of the coring study are to: (1) apply multi-proxy techniques to extract a high resolution (decadal(?) to century scale) of the Quaternary in the McMurdo Sound area; (2) establish marine-terrestrial correlations with geological and ice core records both locally and from elsewhere in Antarctica (e.g., Dry Valleys and Antarctic Peninsula Quaternary geological records; Taylor and Siple Dome ice core records); (3) test Antarctic variability with records from the Northern Hemisphere for cross-hemispheric comparisons; (4) determine the age of MSV unconformity that may well reflect glacial cutting within the MSV by Mackay Glacier during past Quaternary expansion(s) and provide constraints on Neogene erosion rates; and (5) characterize older Quaternary and/or Neogene(?) sediment below the unconformity that potentially could also provide information on Pliocene history of the area. However, before a proposal to achieve these overarching goals can be properly developed, high quality site survey information is required. This work will provide the site data needed for a full assessment of the potential for acquiring high-resolution records of environmental change in the MSV.
